Clean Outline HDRP samples Depth and Normal data in post-processing shader to create fullscreen outlines.

Providing quite some parameters to tune the final outline result.

Friendly for low-poly games if you want a global outline effect instead of setting up outlines in materials for each object.

You can also use Custom Pass to draw HDR highlighted outlines by layer or renderers, highlighted outlines can be blocked by objects or can be seen through. As HDR color is used for Custom Pass outline, glow effect can be added with HDR color and Bloom.

Out of box and easy to use.

Requirement : Unity 2021+ HDRP

Limitation : Post-Processing outlines cannot work with transparent objects, requires opaque objects to have depth and normal drawn on the screen.